On the Nature of the Universe (Oxford World’s Classics) (31 page)

In front of it, and so this first we sense

Before we see the object in the mirror;

That is why it appears to be so far within it.

Wherefore again and yet again I say

It is by no means right to be surprised

At this appearance of objects reflected

In the surface of a mirror, since they involve

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A double journey with two streams of air.

Now why is it that the right side of our body

Appears in a mirror on the left? This is because

When the approaching image strikes the mirror

It is not turned round intact, but flung straight back

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In reverse, as if someone should throw a mask

Of plaster before it is dry against a pillar

So that it bounces straight back keeping the features

Set on its front, but showing them in reverse.

In this case what was the right eye would become

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The left, and the left eye again the right.

An image may also pass from mirror to mirror

So that five or six reflections are produced.

For things can be out of sight at the back of a house

And yet however far removed they are

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Through twisting passages can all be brought out

By a number of mirrors, and be seen to be inside.

So does the image shine from mirror to mirror.

And when the left is given it comes back right

And then comes back again turned round to the same position.

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Moreover, mirrors that have small sides that are curved

In the same degree as our sides send back images

Right to our right and unreversed. Either

Since the image is carried across from mirror to mirror

And then flies to us having been twice reflected,

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Or since the image is turned round when it approaches

As the curved shape of the mirror turns it towards us.

Sometimes the images march along with us

Keeping step with us and mimicking our gestures.

This is because if you move from a part of a mirror

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At once the images cannot return from that part.

Nature compels all things that strike a mirror

To be reflected back at equal angles.

Now here is another thing: the eyes avoid

Bright objects and refuse to gaze at them.

The sun will blind you if you stare at it.

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This is because its power is very great

And from on high through the pure air the images

Travel with great momentum and strike the eyes

And in so doing disrupt the structure of them.

And any strong brightness often burns the eyes

For the reason that it contains many seeds of fire

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Which cause pain to the eyes by piercing them.

People with jaundice see everything yellow.

This is because many seeds of yellow colour

Stream from their bodies to meet the images of things;

And many such seeds are mingled in their eyes

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And by their contact paint everything with pallor.

Again, we see in the dark things in the light

Because, when the black air of darkness, being nearer,

Has entered our eyes and taken possession of them

There follows immediately a bright clear air

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Which purifies them as it were and scatters

The black shades of the first air; for this bright air

Is made of particles much more minute

And much more mobile and more powerful;

As soon as this has filled the paths of the eyes

And opened them, which previously were beset

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By the black air, at once the images of things

That are in the light follow and make us see them.

But on the contrary, we cannot see

Out of the light things that are in the dark,

And this is why: a grosser air of darkness

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Follows behind, fills every pore, blockades

The channels of the eyes, so that no images

Thrown off from things in any way can move them.

And when we see the square towers of a city

From far away, they often appear to be round.

This is because every angle when seen at a distance

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Is blurred, or rather is not seen at all.

Its flow is lost, it does not strike our eyes,

And the air, while the images travel so far through it,

Inflicts many blows upon them and blunts them.

So when every angle has escaped our vision

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The stone structures appear as though turned on a lathe,

Not like things really round that are seen close to,

But in a shadowy way they mimic them.

Our shadow also appears to move in the sun,

To follow our footsteps, imitate our gestures,

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If you can conceive that air without light can walk

And follow the movements and gestures of men;

For what we are accustomed to call shadow

Can be nothing else than air deprived of light.

Doubtless because the air in certain places

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One after another is deprived of the sun’s light

Wherever in our movements we obstruct it,

And the point which we have left is filled again;

That is why the successive shadows of our body

Seem to be the same shadow always following us.

For always new rays of light are pouring out

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And the first are consumed, like wood thrown into a flame.

Thus easily the earth is robbed of light

And is replenished as it washes away

The stain of the black shadows darkening it.

And here we do not concede in any way

That the eyes are deluded. For their task it is

To see in what place light is, and where shadow;

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But whether one light is the same as another,

Whether the shadow that was here is now moving there,

Or rather what happens is what I have just described,

That the mind’s reasoning power must discern.

Eyes cannot understand the nature of things.

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Do not then blame the eyes for this fault of the mind.

A ship we sail in moves while it seems to stand still.

A ship at anchor seems to be passing by,

And hills and plains appear to fly astern

When we drive our vessel past them with flying sails.

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The stars in all the vaults of heaven seem fixed

And still, yet all are in constant motion,

Since to their distant setting they return

When with bright bodies they have crossed the sky.

The sun and moon likewise seem to stand still

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In their places, though the facts show that they move.

In the midst of the ocean mountains rise far off,

Between them lies a channel for a fleet,

And yet they seem to form a single island.

When children spinning round have come to a stop

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They seem to see halls and pillars whirling round

So vividly that they can scarce believe

That the whole roof will not fall in on them.

And when with flickering fires nature begins

To lift her red glow on high, above the hills,

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The glowing sun seems to be close upon them

And touching them with its own heat and fire.

Yet scarce two thousand bowshots are they distant

Or even five hundred throws of a javelin;

But far between them and the sun there lie

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Enormous tracts of ocean spread below

Vast regions of the sky, and many thousands

Of lands lie in between where many men

And varied nations dwell and tribes of beasts.

A puddle no more than a finger deep

Lying between stones on a paved highway

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Gives a view downwards below the earth as far

As the expanse of sky that yawns above,

So that you seem to look down upon the clouds

And see the heavenly bodies wonderfully

Deep-buried in a heaven below the earth.

Again, when in midstream our lively horse

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Stands fast, and we look down upon the waves

Of the river flowing rapidly, a force

Seems to be carrying his body sideways

And to push it violently against the stream,

And wherever we turn our eyes, everything seems

To be rushing and flowing in a similar way.

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A colonnade of equal width throughout

Supported by pillars of equal height